Robert Coats

('91 C4, 57k miles)

My brakes squeal under moderate pressure after warming up. Under light or heavy pressure, they are nice and quiet.

So, does the 964's brakes use any kind of anti-squeal shim or spring?

Assuming the pads and brake rotors are in good shape, how likely is it a bad shim/spring is the problem?

Also, looking down the road to a possible brake job, can the rotors (front and rear) be removed (C4) without having to loosen or disconnect any of the hydraulic lines?

Can I just "hang" the caliper up out of the way?

How about wheel bearings (again, C4, if it matters)? Are they sealed on the 964, or loose and require greasing?

Adrian

Dear Robert,
Yes the 964 calipers use an anti-squeal device. The main cause of brake squealing is corrosion in the the caliper itself where the brake pad sits. All the data you need is in the Porsche Maintenance manual (latest revision) or there is a couple of TSBs which detail what you need to do. Of course before you go delving too deep, check the pads you are using and the disks. Pagid Oranges for instance squeal like a stuck pig. Eh! Anatol,
Ciao,
Adrian
911C4

Brake Vibration Damper - New Application Information
Group4
Number
9310
Model
All
Part Identifier
4745
August 5, 1993
Subject:
Brake Vibration Damper Application
ATTENTION:
Service Manager / Service Technician
This bulletin replaces Technical Bulletin Group 4, Number 9204, Book I, pages 95-98.
Models Affected:
968 from Model Year '92 (N)
944 S2, 944 Turbo from Model Year '87 (H)
911 Carrera 2 and 911 Carrera 4
from Model Year '89 (K)
911 Turbo from Model Year '91 (M)
928 S4, 928 GT from Model Year '88 (J)
928 GTS
Concern:
Application of vibration dampers and damping plates.
Vehicle Information:
A new version damping plate with steel clip (formerly plastic clip) is installed on 911 Carrera 2/4 rear axle from production date: April 2, 1991.
VIN:
96_MS 41 1418 Coupe
96_MS 44 0719 Targa
96_MS 46 2026 Cabriolet
928 S4/GT rear axle from production date: April 12, 1991
VIN: 92_MS 81 0362
Use only new version damping plates when replacing damping plates on 911 C2/4 all Model Years and 928 S4/GT from Model Year '88 (J).
Refer to application chart for part numbers.
Carrera 2 Only
Rear brake calipers with shorter pistons were installed during production from VIN:
96_LS 45 1 922 up to 96_LS 45 2002 Coupe
96_LS46 0623 up to 96_LS 46 0662 Targa
96_LS47 1544 up to 96_LS 47 1780 Cabriolet
When repairing cars for brake noise from rear brakes within the above VIN range, measure vibration damper length (see Figure 1). If old version 24 mm long is installed, replace with new version 23 mm long, Part Number 964 352 963 01. Part Number 964 352 963 00 (24 mm long) is no longer available.
General Information:1. Customer complaints of objectionable brake noise on certain vehicles require that the technician first inspect the vehicle for the existence of vibration dampers and damping plates.
2. When reinstalling/replacing brake pads, damping plates with adhesive surface must be replaced.
Do not reuse damping plates with adhesive surface.
3. When removing brake pads, use a small spatula to separate damping plates from brake pads. Do not damage caliper piston dust caps.
Very Important:
Clean seating and guide surface of brake caliper with mineral spirits before installing vibration dampers and pads. Lubricants or grease must not be used in conjunction with vibration dampers. A light coat of sliding lubricant (Optimoly HT, Part Number 000 043 004 00) may be applied on the guide surface of the pad carrier plate (Figure 2).
Vibration damper and damping plate application chart
Install adhesive tape PNA 999 005 between vibration dampers and brake pads. Clean vibration damper backing plate. Apply adhesive tape to backing plate and cut to size. Peel off protective paper after installing vibration damper in caliper.
For additional information, refer to Technical Bulletins, Book E, Group 4, Number 8810 and Book F, Group 4, Number 8907.